(mouse-wheel-buttons): Map old-style wheel buttons to actual wheel eventsscratch/mouse-wheel-buttons

Change the handling of the old X11 convention to use mouse-4/5/6/7
events to represent wheel events: instead of asking downstream
packages to use the `mouse-wheel-*-event` variables to know which events
represent wheel events, use new var `mouse-wheel-buttons` to directly
convert those events into the standard `wheel-up/down/left/right` events
used everywhere else.

This will simplify the work of packages which can thus just bind their
commands to `wheel-up/down/left/right`.

* lisp/mouse.el (mouse-wheel-buttons): New custom variable.

* src/keyboard.c (make_lispy_event): Adjust for "wheel-clicks" on the tab-bar.
* src/xterm.c (x_construct_mouse_click): Add `xi2` argument and
obey `mouse-wheel-buttons` variable.
(handle_one_xevent): Adjust calls accordingly.
(syms_of_xterm): Define the `mouse-wheel-buttons` and the
`wheel-up/down/left/right`symbols.

* lisp/xt-mouse.el: Don't require `mwheel` any more.
(xterm-mouse--same-button-p): Delete function.
(xterm-mouse--read-event-sequence): Use `mouse-wheel-buttons`.

* lisp/mwheel.el (mouse-wheel-up-event, mouse-wheel-down-event)
(mouse-wheel-left-event, mouse-wheel-right-event): Make obsolete.
(mouse-wheel-obey-old-style-wheel-buttons): Delete variable.

2 files changed, 54 insertions, 12 deletions

diff --git a/src/keyboard.c b/src/keyboard.c
index 91faf4582fa..a06c9116d24 100644
--- a/src/keyboard.c
+++ b/src/keyboard.c
@@ -6639,8 +6639,17 @@ make_lispy_event (struct input_event *event)
 
         if (CONSP (event->arg))
           return list5 (head, position, make_fixnum (double_click_count),
-                        XCAR (event->arg), Fcons (XCAR (XCDR (event->arg)),
-                                                  XCAR (XCDR (XCDR (event->arg)))));
+                        XCAR (event->arg),
+                        /* FIXME: When a mouse-click on a tab-bar is
+                           converted into a wheel-event we get here something
+                           of an unexpected shape...  */
+                        (CONSP (XCDR (event->arg))
+                         && CONSP (XCDR (XCDR (event->arg))))
+                        ? Fcons (XCAR (XCDR (event->arg)),
+                                 XCAR (XCDR (XCDR (event->arg))))
+                        /* ... not knowing what this "unexpected shape" means,
+                           we just use nil.  */
+                        : Qnil);
         else if (NUMBERP (event->arg))
           return list4 (head, position, make_fixnum (double_click_count),
                         event->arg);
diff --git a/src/xterm.c b/src/xterm.c
index c0aef65ab66..5e5eb6269e4 100644
--- a/src/xterm.c
+++ b/src/xterm.c
@@ -14551,18 +14551,19 @@ x_query_pointer (Display *dpy, Window w, Window *root_return,
    `x', `y', `x_root' and `y_root'.  This function should not access
    any other fields in EVENT without also initializing the
    corresponding fields in `bv' under the XI_ButtonPress and
-   XI_ButtonRelease labels inside `handle_one_xevent'.  */
+   XI_ButtonRelease labels inside `handle_one_xevent'.
+
+   XI2 indicates that this click comes from XInput2 rather than core
+   event.   */
 
 static Lisp_Object
 x_construct_mouse_click (struct input_event *result,
                          const XButtonEvent *event,
-                         struct frame *f)
+                         struct frame *f, bool xi2)
 {
   int x = event->x;
   int y = event->y;
 
-  /* Make the event type NO_EVENT; we'll change that when we decide
-     otherwise.  */
   result->kind = MOUSE_CLICK_EVENT;
   result->code = event->button - Button1;
   result->timestamp = event->time;
@@ -14572,6 +14573,29 @@ x_construct_mouse_click (struct input_event *result,
                           ? up_modifier
                           : down_modifier));
 
+  /* Convert pre-XInput2 wheel events represented as mouse-clicks.  */
+  if (!xi2)
+    {
+      Lisp_Object base
+        = Fcdr_safe (Fassq (make_fixnum (result->code + 1),
+                            Fsymbol_value (Qmouse_wheel_buttons)));
+      int wheel
+        = (NILP (base) ? -1
+           : BASE_EQ (base, Qwheel_down)  ? 0
+           : BASE_EQ (base, Qwheel_up)    ? 1
+           : BASE_EQ (base, Qwheel_left)  ? 2
+           : BASE_EQ (base, Qwheel_right) ? 3
+           : -1);
+      if (wheel >= 0)
+        {
+          result->kind = (event->type != ButtonRelease ? NO_EVENT
+                          : wheel & 2 ? HORIZ_WHEEL_EVENT : WHEEL_EVENT);
+          result->code = 0;         /* Not used.  */
+          result->modifiers &= ~(up_modifier || down_modifier);
+          result->modifiers |= wheel & 1 ? up_modifier : down_modifier;
+        }
+    }
+
   /* If result->window is not the frame's edit widget (which can
      happen with GTK+ scroll bars, for example), translate the
      coordinates so they appear at the correct position.  */
@@ -21881,13 +21905,14 @@ handle_one_xevent (struct x_display_info *dpyinfo,
                         && event->xbutton.time > ignore_next_mouse_click_timeout)
                       {
                         ignore_next_mouse_click_timeout = 0;
-                        x_construct_mouse_click (&inev.ie, &event->xbutton, f);
+                        x_construct_mouse_click (&inev.ie, &event->xbutton,
+                                                 f, false);
                       }
                     if (event->type == ButtonRelease)
                       ignore_next_mouse_click_timeout = 0;
                   }
                 else
-                  x_construct_mouse_click (&inev.ie, &event->xbutton, f);
+                  x_construct_mouse_click (&inev.ie, &event->xbutton, f, false);
 
                 *finish = X_EVENT_DROP;
                 goto OTHER;
@@ -21957,13 +21982,15 @@ handle_one_xevent (struct x_display_info *dpyinfo,
                           && event->xbutton.time > ignore_next_mouse_click_timeout)
                         {
                           ignore_next_mouse_click_timeout = 0;
-                          x_construct_mouse_click (&inev.ie, &event->xbutton, f);
+                          x_construct_mouse_click (&inev.ie, &event->xbutton,
+                                                   f, false);
                         }
                       if (event->type == ButtonRelease)
                         ignore_next_mouse_click_timeout = 0;
                     }
                   else
-                    x_construct_mouse_click (&inev.ie, &event->xbutton, f);
+                    x_construct_mouse_click (&inev.ie, &event->xbutton,
+                                             f, false);
 
                   if (!NILP (tab_bar_arg))
                     inev.ie.arg = tab_bar_arg;
@@ -23740,13 +23767,13 @@ handle_one_xevent (struct x_display_info *dpyinfo,
                                 && xev->time > ignore_next_mouse_click_timeout)
                               {
                                 ignore_next_mouse_click_timeout = 0;
-                                x_construct_mouse_click (&inev.ie, &bv, f);
+                                x_construct_mouse_click (&inev.ie, &bv, f, true);
                               }
                             if (xev->evtype == XI_ButtonRelease)
                               ignore_next_mouse_click_timeout = 0;
                           }
                         else
-                          x_construct_mouse_click (&inev.ie, &bv, f);
+                          x_construct_mouse_click (&inev.ie, &bv, f, true);
 
                         if (!NILP (tab_bar_arg))
                           inev.ie.arg = tab_bar_arg;
@@ -32452,6 +32479,12 @@ syms_of_xterm (void)
   DEFSYM (Qexpose, "expose");
   DEFSYM (Qdont_save, "dont-save");
 
+  DEFSYM (Qmouse_wheel_buttons, "mouse-wheel-buttons");
+  DEFSYM (Qwheel_up,    "wheel-up");
+  DEFSYM (Qwheel_down,  "wheel-down");
+  DEFSYM (Qwheel_left,  "wheel-left");
+  DEFSYM (Qwheel_right, "wheel-right");
+
 #ifdef USE_GTK
   xg_default_icon_file = build_pure_c_string ("icons/hicolor/scalable/apps/emacs.svg");
   staticpro (&xg_default_icon_file);